Manufacturing a radial tire and apparatus for practicing said method

ABSTRACT

A method of manufacturing a tire comprises a first process including the steps of forming a carcass ply or the like to a cylindrical configuration, placing bead cores on the cylindrical carcass ply and then effecting assembly of a carcass ply-bead core structure. A second process of the method includes the steps of receiving the structure from the last step in the first process, effecting assembly of a cylindrical carcass layer and then deforming the latter into a trochoidal configuration to obtain a green tire, wherein the carcass ply located between both the bead cores on the structure is caused to expand either in the first process or in the second process. The structure is placed on a drum device in the second process, the bead cores are wrapped with the end portions of the carcass ply and then the green tire for the radial tire is assembled by attaching side wall members or the like. Further, according to other aspect of the present invention an apparatus for practicing the above-described method is also disclosed.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a method of manufacturing a radial tireand an apparatus for practicing said method.

As is well known, a conventional method of manufacturing a radial tireis generally classified into a single stage type molding method and adouble stage type molding method.

The single stage type molding method is practiced by way of the steps offirst winding a material for a carcass layer on a drum device which isdesigned so as to expand and contract, placing bead cores at thepredetermined position, allowing the drum device to expand so as todeform the cylindrical configuration into a trochoidal one, and thenwinding a breaker ply and a tread thereon or allowing the carcass layerto expand to the inner wall of a breaker-tread structure which ispreviously prepared.

On the other hand, the double stage type molding method is practiced byway of the steps of assembling a cylindrical carcass layer on a drumdevice in the first stage, said drum device being designed so as toexpand and contract, removing the carcass ply from the drum device totransport the same, placing the carcass layer on another drum device inthe second stage, said drum device being designed so as to expand andcontract, deforming the cylindrical configuration of the carcass layerinto a trochoidal one and then winding a breaker ply and a tread orallowing the carcass layer to expand to the inner wall of abreaker-tread structure which is previously prepared.

As is apparent from the above description, the single stage type moldingmethod is free from the troublesome operation in the double stagemolding method which comprises the step of displacing the cylindricalcarcass layer from the drum device in the first stage to the drum devicein the second stage, but it includes a number of problems because it isnecessary to exactly locate a material to be assembled and effect firmassembling under pressure. Further, another disadvantageous feature ofthe single stage type molding method is that a distance between theadjacent cords is not distributed uniformly in the peripheral directionwhile the carcass ply is kept in an expanded state, because the carcassply is expanded and comes in tight contact with the lower part of thebead cores, after the latter are placed on the cylindrical carcass ply.

Besides this a modified method is also proposed which includes the stepsof previously assembling a carcass ply to a cylindrical configuration,transporting the assembled carcass ply to a drum device in the secondstage with the aid of a transporting device, said drum device beingdesigned so as to expand and contract, placing bead cores outward of thecarcass ply, and then allowing the carcass ply to expand toward thelower portion of the bead cores so that they are brought in pressurecontact with one another. However, it is found that the modified methodhas a drawback that during the pressure contact therebetween thecylindrical carcass is caused to expand and thereby fiber distributiondensity in the material loses its uniformity.

Further, another modified method is proposed which includes the steps ofpreviously assembling a carcass ply to a cylindrical configuration,locating bead cores on the assembled carcass ply, allowing the latter toexpand toward the lower area of the bead cores so that they are broughtin pressure contact with one another while the bead cores are subjectedto expansion, transporting the carcass ply-bead core assembled structureto a drum device in the second stage which is designed so as to expandand contract, and then effecting tire molding on said drum device.However, it is also found that the above second modified method has thesame drawback as that of the preceding modified method, that is, fiberdistribution density in the carcass ply loses its uniformity.

On the other hand, the double stage molding method is preferablypracticed with the aid of a so-called high crown type drum which isdesigned so as to expand and contract for the purposes of ensuring thatthe material in the vicinity of the bead cores is hardly deformed ordislocated when a trochoidal configuration is achieved in the secondstage as well as when final molding is effected in a vulcanizing dieassembly.

However, it is found that a trouble or failure tends to occur with thehigh crown type drum during the step of winding a carcass ply, becauseit has an outer diameter which is substantially larger than the innerdiameter of the bead cores.

Specifically, due to the arrangement that the bead cores are wrappedwith the end portions of the carcass wound around an increased diametera trouble or failure occurs that wrinkles appear in the vicinity of thebead cores when deforming the carcass inwardly in the radial direction(to achieve a reduced diameter). Another drawback is that incorrectlocation of the ply cords in the vicinity of the bead cores has aneffect on incorrect location of the ply cords when deforming to atrochoidal configuration on the drum device in the second stage.

In order to obviate the drawbacks as described above to some extent amodified method is preferably employed which includes the steps ofpreparing a cylindrical carcass ply which has a diameter close to thatof the bead cores, transporting it to a drum in the first stage, placingthe bead cores on the carcass ply with the drum in the first stageexpanded and thereby making a preparation prior to wrapping the beadcores.

It is true that the modified method has an advantage that no wrinkleappears. However, it is found that incorrect location of the ply cordsoccurs unavoidably at the shoulder parts of the drum, because sectorpieces for constituting the drum surface are displaced as the drum iscaused to expand.

The ply cords at the bead portions are held in a substantially correctlocation but they are not in a perfectly correct location. It should benoted that the incorrect location of the above-described type can not beremedied during the step of deforming to a trochoidal configuration.

SUMMARY OF THE INVENTION

Thus, the present invention is intended to perfectly obviate thedrawbacks inherent in the conventional methods as described above.

It is an object of the present invention to provide a method ofmanufacturing a radial tire at a substantially increased dimentionalaccuracy and improved productivity.

It is an other object of the present invention to provide an apparatusfor practicing the above-described method.

Specifically, the present invention consists in an improved method ofmanufacturing a tire which essentially comprises a first and a secondprocess, said first process including the steps of forming a carcass plyor the like to a cylindrical configuration, placing bead cores on thecylindrical carcass ply and then effecting assembly of a carcassply-bead core structure, while said second process including the stepsof receiving the structure transported from the last step in the firstprocess, effecting assembly of a cylindrical carcass layer and deformingthe latter into a trochoidal configuration to obtain a green tire,wherein the carcass ply located between both the bead cores of thestructure is caused to expand either in the first process or in thesecond process. The structure is placed on a drum device in the secondprocess, the bead cores are wrapped with the end portions of the carcassply and then the green tire for the radial tire is assembled byattaching side wall members and others.

Since an arrangement is made such that the carcass ply-bead corestructure is correctly assembled in the first process and the carcassply located between both the bead cores is caused to expand previouslyprior to placing the structure on the drum device in the second process,it is ensured that an occurrence of irregular distribution of a distancebetween the adjacent ply cords at the drum shoulder portions iseffectively prevented. Further, since an arrangement is made such thatthe carcass ply is deformed to a trochoidal configuration and then thegreen tire is assembled without any necessity for displacement of thecylindrical carcass layer, it is ensured that no troublesome operationsuch as removal, transportation and location of the cylindrical carcasslayer is required. Furthermore, since an arrangement is made such thatassembling of the carcass ply-bead core structure and completion of thegreen tire are effected in a separate step respectively, it is ensuredthat manufacturing is effected at an excellent efficiency.

Hence, it is possible to effect manufacturing of a green tire in astrictly exact manner and with improved productivity.

Further, the present invention consists in an apparatus formanufacturing a radial tire which essentially comprises a pair ofsymmetrically located shoulder formers including a plurality of sectorpieces which are expandable and contractive in the radial direction, apair of symmetrically located bead lock seals located outward of saidshoulder formers, said bead lock seals being also expandable andcontractive in the radial direction, and a pair of symmetrically locatedturnup bladders located outward of said bead lock seals, said turnupbladders being expandable in the radial direction, wherein the shoulderformers, the bead lock seals and the turnup bladders are constructed soas to move toward or away from the oppositely located one in asynchronous and symmetrical relation.

Since the apparatus of the present invention as described above makes itpossible to effect wrapping of the bead cores with the end portions ofthe carcass ply and attaching of the side wall members and others on apractically solid cylindrical configuration generated by means of theshoulder formers during the assembling of the cylindrical carcass layer,it is ensured that assembling is effected in a strictly exact manner.Further, since an arrangement is made such that the shoulder formers,the bead lock seals and the turnup move toward or away from theoppositely located one in a synchronous and symmetrical relation, it isensured that assembling of the cylindrical carcass layer is effected onthem and at the same time expansion of the carcass layer located betweenboth the bead cores and deformation of the same into a trochoidalconfiguration are effected with a distance between both the bead coresreduced.

Other objects and advantageous feature of the present invention will bereadily apparent from a reading of the following description made inconnection with the accompanying drawings which illustrate a preferredembodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Now the present invention will be described in a greater detail withreference to the accompanying drawings in which:

FIG. 1 is a plan view of the whole system to which the present inventionis applied.

FIG. 2 is a front view of the system in FIG. 1.

FIG. 3 is a vertical sectional view of a carcass band assembling formerA.

FIG. 4 is a partial sectional view of an essential part of the carcassband assembling former A, shown on an enlarged scale.

FIG. 5 is a schematic perspective view of a normally corrugated carcassply deformed from a cylindrical configuration.

FIG. 6 is a front view of a transporting device C of which the upperpart is shown in a sectional view.

FIGS. 7(a) to (d) are each a partial sectional view of a carcass formingdrum respectively, wherein four different operative positions are shownin both the upper and lower parts of the drawings.

FIGS. 8(a) to (f) are each a schematic front view illustrating assemblyoperations for a carcass band-bead core structure respectively, and

FIGS. 9(a) to (i) are a schematic front view illustrating assemblyoperations for a green tire respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the accompanying drawings, FIG. 1 is a plan viewillustration of an arrangement of the whole system where a method inaccordance with the present invention is practiced and FIG. 2 is a frontview of the system in FIG. 1, wherein reference letter A designates acarcass band assembling former on which a carcass band is assembled andthe assembled band includes bead cores wound therearound, referenceletter B designates a supply device for delivering materials requiredfor the assembly of the carcass band, reference letter C designates atransporting device for an assembly of the carcass band and the beadcores, reference letter D designates a carcass forming drum on which alayered structure of the carcass is cylindrically shaped and then thecylindrical carcass structure is deformed to a trochoidal shape,reference letter E designates a supply device for delivering materialsrequired for the cylindrical carcass structure, and reference numeral Fdesignates a pushing device for serving to wrap the bead core portion onthe left-hand side of drum D. It should be noted that said pushingdevice may be omitted when the carcass forming drum D is equipped with adouble bladder. Further, reference letter G designates a pushing deviceserving to wrap the bead core portion on the right-hand side of drum D,reference letter H designates an assembling drum for a breaker treadstructure, reference letter I designates a supply device for deliveringmaterials required for the breaker tread structure, and reference letterJ designates a transporting device for the breaker tread structure.

First, the carcass band assembling former A will be described below.

As shown in FIG. 3, the carcass band assembling former A comprises a plyformer 21 and a bead holder 22, said ply former 21 being coaxiallyarranged on a shaft 20 so as to rotate together with the shaft 20.

The ply former 21 includes a sleeve 23, discs 24 radially extending atboth the end parts of said sleeve 23, said discs 24 being formed with agroove 25 respectively, a plurality of sector-shaped segments 26 with apredetermined number of magnets 26_(a) firmly embedded on the outersurface thereof, guides 27 extending inwardly from said segments 26 tobe slidably fitted into said grooves 25, stoppers 28 serving to define aradial displacement of said guides 27 and a plurality of hydrauliccylinder units 29 disposed between the segments 26 and the sleeve 23.The sector-shaped segments 26 are radially extendable within an extentas defined by means of the stoppers 28. When the segments 26 areextended to the outermost position, their outer surfaces generate aclosed cylindrical surface whose diameter is smaller than the innerdiameter of the bead cores by the thickness of a material (carcass ply)to be wound. On the other hand, when they are extended inwardly in theradial direction they are located at the contacted position where theirdiameter is substantially smaller than the inner diameter of the beadcores. It should be noted that the grooves 25, the guides 27 and thestoppers 28 are dimensioned so that the segments 26 are alternatelylocated at the innermost contracted position when they are displacedinwardly.

Specifically, an arrangement is made such that the segments 26 of whichradial displacement is dimentioned larger than that of the adjacentsegments 26 are first displaced inwardly in the radial direction andsubsequently the latter ones are displaced inwardly in the samedirection so that all the segments 26 are located in close contact withone another in a side-by-side relation when they reach the innermostcontracted position. The time lag determined for delayed displacement ofthe latter segments 26 is controlled by the time when hydraulic liquidis delivered to the corresponding hydraulic cylinder units 29.

As shown in FIG. 4, the ply former 21 is provided with a bead lockdevice 30 in the vicinity of both the ends of the respective segments 26where the bead cores are to be located, said bead lock device 30 havinga width sufficiently larger than the thickness of the bead cores andbeing adapted to protrude outward of the segment 26. Specifically, thebead lock device 30 includes a segment 32 with a resilient member 31received in a recessed part on the segment 26, a plurality of pins 33extending downwardly from said segment 32 to slide through the holes onthe segment 26 which serve as guide means and a hydraulic cylinder unit34 disposed between both the segments 26 and 32. The resilient member 31has an outer surface with a curvature which is dimensioned to be thesame as to that of the segment 26 and thereby the outer surface of themember 31 becomes flush with that of the latter when the former isreceived in the recessed part on the segment 26.

In the meanwhile, the bead holder 22 is located at the shaft end part ofthe ply former 21 where no bearing is provided and comprises a holderhalf 35 for the left-hand bead core and a holder half 36 for theright-hand bead core. The respective holder halves 35 and 36 areconstructed of a plurality of sector pieces and are mounted on theperipheral portion of a radially extending hub 37 which is fixedlymounted on the shaft 20, wherein air bags 38 and 39 adapted to expand orcontract individually in the radial direction are disposed between thesector pieces for the holder halves 35 and 36 and the peripheral flangeportion of the hub 37 and the air bags 38 and 39 and the sector piecesfor the holder halves 35 and 36 are guided in the radial direction bymeans of the vertically extending walls on the peripheral flange portionof the hub 37. The bead core seating surface of the sector pieces isdimensioned a little larger than the inner diameter of the bead corewhen they expand to the outermost limit, whereas it is dimensionedsubstantially smaller than the inner diameter of the bead core and thecarcass ply wound around the ply former 21 when they contract to theinnermost limit.

After a carcass ply, inner liner or the like is wound on the former A asconstructed in the above-described manner, the segments 26 arealternately contracted inwardly in the radial direction whereby thecarcass ply is resiliently deformed to a cylinder having a normallycorrugated (trochoidal) surface as illustrated in FIG. 5 and thereby ithas an outer diameter which is smaller than the inner diameter of thebead core.

After the bead core is located at the predetermined position, thesegments 26 are displaced outwardly in the radial direction and at thesame time the segments 32 as illustrated in FIG. 4 are extendedoutwardly. As a result the carcass ply is brought in pressure contactagainst the inner surface of the bead cores.

After completion of the assembling of the carcass ply and the bead coresthe assembled structure can be removed from the former A with the aid ofthe transporting device C when the segments 26 and 32 and the holderhalves 35 and 36 on the bead holder 21 are contracted inwardly so as toallow their outer diameter to be reduced.

As is well known, the material supply device B is designed andconstructed in a variety of types and any suitable one is available forthe present invention. Thus, further detailed description will not berequired.

As shown in FIG. 6, the transporting device C includes bead holdingdevices C₁ and C₂ for serving to hold the bead cores in thepredetermined position which have been prepared in the aforesaid formerA, an outward expansion limiting device C₃ for defining a radialexpansion of the carcass ply intermediate the bead cores and a movingwagon C₄ adapted to reciprocably move between the former A and thecarcass forming drum D.

The moving wagon C₄ is equipped with wheels 41 rolling on rails 40 and achassis 42 carries an annular member 43 which is disposed in a coaxialrelation relative to the shaft 20.

The annular member 43 includes cylindrical guide surfaces at both theend parts thereof which extend in a coaxial relation relative to theshaft 20 and the former A. Further, the annular member 43 includessleeves 44 slidably mounted thereon, said sleeves 44 being fixedlysecured to the bead holding devices C₁ and C₂, and it is formed withradially extending projections onto which a plurality of hydrauliccylinder units 45 are fixedly secured so as to allow the bead holdingdevices C₁ and C₂ to be axially displaced.

A sector-shaped member 46 for the outward expansion limiting device C₃is adapted to be radially displaced by means of a hydraulic actuator 47while it is guided with the aid of members 46'.

Further, the moving wagon C₄ is provided with a conventional mechanismfor stopping it at the former A and the carcass forming drum D as wellas a control device mounted thereon.

The bead holding device C₁ includes a sleeve 44 slidably mounted on theannular ring 43, a plurality of arms 48 adapted to swing on the sleeve44, said arms 48 being fitted with a magnet 48 at the extreme endthereof respectively, a plurality of hydraulic cylinder units 50 ofwhich one end is connected to the arm 48 and of which other end isconnected to the sleeve 44, and a plurality of hydraulic cylinder units45 of which one end is connected to the radial projection 51 on thesleeve 44 and of which other end is connected to the radial projection43' on the annular ring 43.

As the hydraulic cylinder units 50 extend and thereby the arms swing inthe clockwise direction as seen in the drawing, the respective magnets49 are inwardly displaced in the radial direction to reach a positionwhere they are engaged with the metal wire portion of the bead core butthey are not brought in contact with the material wound on the former A.

The bead holding device C₂ is designed and constructed in quite the samemanner as the aforesaid bead holding device C₁. Thus, the bead holdingdevices C₁ and C₂ occupy any required axial position on the annular ring43 respectively and the arms 48 swing to any required angular position.

Further, the outward expansion limiting device C₃ includes a pluralityof sector pieces 46 radially displaceably suspended from the annularring 43, a plurality of hydraulic cylinder units 47 for radiallydisplacing the corresponding sector piece 46 and a number of magnets 52firmly embedded in recessed parts on the inner surface of the respectivesector pieces 46.

An arrangement is made such that the sector pieces 46 on the outwardexpansion limiting device C₃ are inwardly displaced in the radialdirection alternately by a different distance and specifically one groupof the alternately disposed sector pieces 46 have a radial displacementlonger than that of the other group so that they come in contact withthe carcass ply on the former A when they are displaced to the innermostlimit.

When the outward expansion limiting device C₃ expands to a midwayposition, a closed cylindrical surface is formed with the aid of all thesector segments 46, whereas when it expands to the outermost limit, theyare located a little outward of said cylindrical surface.

The above-described device is intended to be applied particularly to asteel cord reinforced carcass ply but it should not be limited only tothis. As is known, the device may be employed for a textile cordreinforced carcass ply.

The magnets 26_(a) on the former A are effective in deforming acylindrical carcass ply into the form of a normally corrugatedconfiguration as illustrated in FIG. 5. On the other hand, the magnets52 on the transporting device C are intended to serve as holding meansduring transportation. Hence, when a textile cord reinforced carcass plyis in use, both the magnets 26a and 52 are inoperative.

It will be readily understood by any expert of the art that in case of atextile cord reinforced carcass ply the magnets 52 on the sectorsegments 46 are replaced with conventional vacuum pad means and that inorder to ensure a normally corrugated deformation conventional devicessimilar to a so-called finger ply down employed for the first stage in amanufacturing line are disposed at both the end parts of the former A.

Next, the carcass forming drum D includes a pair of symmetricallydisposed bead lock turnup devices D₁ and D₂ and a pair of symmetricallydisposed shoulder formers D₃ and D₄ located inward of said devices D₁and D₂, as illustrated in FIGS. 7(a) to (d).

FIG. 7(a) (upper half above a line X--X) illustrates that the shoulderformers D₃ and D₄ are folded inwardly and the bead lock turnup devicesD₁ and D₂ are spaced by the longest distance from one another. FIG. 7(b)(lower half below the line X--X) illustrates that the shoulder formersD₃ and D₄ are expanded and the bead lock turnup devices D₁ and D₂ arelocated closer to one another than in FIG. 7(a). FIG. 7(c) (upper halfabove the line X--X) illustrates that the shoulder formers D₃ and D₄ areexpanded and the bead lock turnup devices D₁ and D₂ are located closestto one another. FIG. 7(d) (lower half below the line X--X) illustratesthat the bead lock turnup devices D₁ and D₂ are located closest to oneanother and the shoulder formers D₃ and D₄ are folded inwardly.

The bead lock turnup devices D₁ and D₂ includes a sleeve 101 slidablymounted on a shaft 100 which is rotatably supported on a stand (notshown), an expandable bead lock seal 103 fitted into a circular grooveon the periphery of a disc 102 radially extending from the sleeve 101and an expandable bladder 104 disposed on a cylindrical extension fromthe disc 102 respectively. The bead lock seal 103 is preferably integralwith the bladder 104 but the former may be separated from the latter (inthe illustrated embodiment the former is integral with the latter).

An arrangement is made such that both the bead lock seal 103 and thebladder 104 are supplied with pressurized air from the outside.

As long as a so-called single bladder is employed for the bladder 104 asshown in the drawing, the pushing devices F and G are required asillustrated in FIGS. 1 and 2. However, when a dual bladder having twolayers on the one side is employed, the pushing devices F and G may beomitted.

The sleeve 101 is operatively connected with a screw rod 105 via a nut106 and a pin 107, said screw rod 105 being rotatably disposed withinthe shaft 100 while said nut 106 being in screw engagement with thescrew rod 105, and said pin 107 extending through a slot 100_(a) formedon the shaft 100.

A difference between both the bead lock turnup devices D₁ and D₂consists in that the screw rod 105 and the corresponding nut 106 arethreaded in the opposite direction to one another. Besides this there isno difference therebetween.

As the screw rod 105 is rotated, the bead lock turnup devices D₁ and D₂move toward one another in a symmetrical manner relative to a centerline Y--Y of the drum, whereas as it is rotated in the oppositedirection, they move away from one another.

Further, as the bead lock seal 103 is supplied with pressurized air, itsouter diameter becomes enlarged and thereby it is brought in pressurecontact with the lower portion of the bead core fitted into a carcassband. As a result an airtight chamber is provided between both thepressure contact portions.

It should be noted that the sleeve 101 is fitted with an air seal member(not shown) so as to ensure no leakage of air through a clearancebetween the shaft 100 and the sleeve 101 during sliding movement of thelatter.

The shoulder formers D₃ and D₄ includes a disc 114 slidably mounted onthe sleeve 101 for the bead lock turnup devices D₁ and D₂, a pluralityof hydraulic cylinder units 108 of which one end is fixedly secured tothe disc 114 and of which other end is fixedly secured to the disc 102,a plurality of rods 109 fixedly secured to the disc 114 to extendthrough the disc 102, a plurality of links 111 of which one is connectedto the free end of the rod 109 and of which other end is connected tothe central part of a link 110 pivotally mounted on the sleeve 101, aplurality of links 112 pivotally mounted on the sleeve 101 in the samemanner as the links 110, and a plurality of shoulder segments 113 withthe upper end of the links 110 and 112 connected thereto respectively,said rods 109 being fitted with an air seal member (not shown) in orderto ensure no leakage of air from the air chamber during sliding movementthereof.

As is apparent from the drawings, the links 110 and 112 have pivotalends which form four corners of a parallelogram.

As the disc 114 is displaced away from the disc 102 by means of thehydraulic cylinder units 108, the shoulder segments 113 are caused toexpand. When they are expanded to the outermost limit, a cylindricalconfiguration is generated by them so as to allow the side wall portionsto be tightly secured in the vicinity of the bead cores.

The material supply device E, the pushing device F and the pushingdevice G are designed and constructed in a variety of types and anysuitable ones are available for the present invention. Thus, no detaileddescription will be required.

Further, the breaker-tread structure assembling drum H is designed inthe form of a practically cylindrical solid drum comprising a pluralityof drum segments, said drum having the outer peripheral length which isequal or is substantially equal to the inner peripheral length of a beltto be assembled when they are expanded but which is shorter than theinner peripheral length of the assembled belt-tread structure when theyare contracted. For instance, a conventional drum as disclosed in theofficial gazette of the prior inventions such as Japanese PatentLaid-Open No. 135,647/80, No. 135,648 or the like is available for thepresent invention.

The drum H as constructed in the above-described manner is mounted in acoaxial alignment with the drum D and the former is adapted to be drivenon the shaft 100 independently of the latter.

Any conventional mechanism for driving the drum H independently of thedrum D is available for the present invention and therefore no detaileddescription will be required.

The material supply device I is also designed and constructed in avariety of types and any conventional one is available. Thus, nodetailed description will be required.

Further, the transporting device J for the breaker-tread structurecomprises a plurality of expandable segments which are designed tosurround the whole breaker-tread structure assembled on the drum H andthen partly or fully hold the outer surface thereof, wherein a mechanismfor expanding or contracting the segment is disposed on a movable wagonwhich is adapted to move on rails. For instance, a conventionaltransporting device as disclosed in the official gazette of the priorinventions such as Japanese patent pulication Nos. 1951/77, 2625/75 orthe like can be employed for the present invention.

Now operation of the apparatus in accordance with the present inventionwill be described below.

First, assembling of the carcass band-bead core structure will bedescribed with reference to FIGS. 8(a) to (f).

As illustrated in FIG. 8(a), the ply formes 21 are expanded to generatea cylindrical configuration, while a material is delivered from thematerial supply device B and then is wound on the former A in accordancewith the predetermined order. During the winding of the material acarcass ply is attracted to the ply former 21 by means of the magnets26_(a).

At a certain time both the bead holder halves 35 and 36 are caused tocontact. First, the left-hand bead core 70 is located on the left-handbead holder half 35 and then the latter is expanded, whereby theleft-hand bead core 70 is firmly held.

Next, the right-hand bead core 70 is firmly held on the right-hand beadholder half 36 in the same manner as the foregoing.

Then, as illustrated in FIG. 8(b), the former A is contracted inwardlyin the radial direction so that the wound carcass ply 80 is deformed tothe configuration as illustrated in FIG. 5.

The transporting device C starts to move from the waiting position andits stoppes at the position where the left-hand bead holding device C₂is ready for holding the left-hand bead core 70. Then, the arm of theholding device swings in the anticlockwise direction until it comes incontact with the core position of the left-hand bead core 70.

Then, as the sector segments of the left-hand bead holder half 36 arecontracted from the position where the left-hand bead core 70 is held,the result is that the latter is transferred to the bead holding deviceC₂.

Next, as illustrated in FIG. 8(c), the transporting device C movesfurther to the left and it stoppes at the position where the right-handbead holding device is ready for holding the right-hand bead core 70.Thus, the latter is held in the same manner as the foregoing.

After completion of the holding of both the left-hand and right-handbead cores 70 the transporting device C moves further to the left andstoppes at the position where both the bead cores are to be located, asillustrated in FIG. 8(d).

Then, the former A is caused to expand and thereby the carcass plydeformed as illustrated in FIG. 5 is restored to the originalcylindrical configuration. As a result the carcass ply 80 is brought incontact with the lower portions of the bead cores 70 as illustrated inFIG. 8(e).

Further, by allowing the segments in the bead lock devices in FIG. 4 toprotrude outward it is ensured that the carcass play located in thevicinity of the lower portions of the bead cores is brought in tightcontact against the lower portions of the bead cores.

Next, the carcass holding device C₃ in the transporting device C isdisplaced inwardly in the radial direction whereby the outer surface ofthe carcass ply 80 is attracted to the magnets 52. Then, the former A iscontracted inwardly in the radial direction. It is preferable that themagnets 26_(a) on the segment pieces on the former A are demagnetizedduring the contraction.

Thus, the assembled structure of the cylindrical carcass ply 80 and thebead cores 70 is held in the transporting device C while the bead coreportions and the intermediate portion of the carcass ply therebetweenare attracted to the magnets.

While the transporting device C is kept in the assembled state asdescribed above, it moves by way of the waiting position and stops atthe drum D.

Next assembling of a green tire on the drum D will be described withreference to FIGS. 9(a) to (i).

Prior to receiving the carcass band-bead core assembled structure thedrum D is kept in the positional state as illustrated in FIG. 7(a).

Specifically, both the bead lock turnup devices D₁ and D₂ and theshoulder former D₃ and D₄ are contracted to the reduced diameter whichis substantially smaller than the inner diameter of the assembledstructure to be transported.

The distance between both the bead lock seals 103 is dimentioned same tothat between both the bead cores on the assembled structure.

After completion of the transportation the carcass band-bead coreassembled structure is located outward of the drum D of which diameterhas been reduced, as illustrated in FIG. 9(a).

Then, the bead lock seals 103 are expanded as illustrated in FIG. 9(b)whereby the lower portions of the bead cores on the assembled structureare held air-tightly.

As the lower portions of the bead cores are held, the bead core holdingdevices C₁ and C₂ on the transporting device C are caused to swingoutwardly as illustrated in FIG. 9(c) whereby the bead cores 70 arereleased from the firmly held state. At the same time the sector pieces46 on the carcass holding device C₃ which are now holding the carcassply between both the bead cores are caused to expand.

The sector pieces 46 stop their expansion at the position where theouter diameter of the carcass ply to be expanded in the next step isdefined.

Next, the interior of the carcass ply airtightly held by means of boththe bead lock seals 103 is supplied with pressurized air and at the sametime both the bead lock turnup devices are caused to move toward oneanother in a symmetrical relation. As a result the carcass ply isexpanded between both the bead cores by pressurized air while itsexpansion is defined to a cylindrical configuration.

Then, the segments 113 on the shoulder former are expanded andthereafter inner pressure is released from the air chamber.

The positional state of the drum device D at this time is as illustratedin FIG. 7(b).

Next, the sector pieces 46 on the outward expansion limiting device areexpanded as illustrated in FIG. 9(e) until they reach a diameter largerthan the outer diameter of the carcass band-bead core assembledstructure on the drum D.

While the above-described positional state is maintained, thetransporting device C moves back to the waiting position and then thepushing device F is located in a coaxial alignment with the drum D.

Next, both the bladders 104 on the bead lock turnup devices are causedto expand and thereafter a part of the expanded bladders 104 ishorizontally urged toward the center of the drum D while it is definedby means of the pushing devices F and G.

This causes the outer parts of both the bead cores of the carcass bandto wrap the bead cores 70 and come in pressure contact against thecarcass ply 80.

During the horizontal expansion and pressure contact as described aboveboth the shoulder formers D₃ and D₄ serves as a pressure support memberrespectively.

While the above-described expansion is effected on the drum H, thebreaker-tread structure assembled on the drum H stands by the drum Dwith the outer part of the structure held by means of the transportingdevice J, as illustrated in FIG. 9(g).

After completion of the step as illustrated in FIG. 9(f) other memberssuch as side wall or the like are attached to the structure whereby acylindrical carcass layer is achieved.

Next, as illustrated in FIG. 9(h), both the shoulder formers D₃ and D₄and both the bead lock turnup devices D₁ and D₂ are caused to movetoward one another in a symmetrical relation while the carcass layer issupplied with pressurized air. As a result the cylindrical carcass layeris deformed to a trochoidal configuration.

At a certain time during the above step of operation the previouslyprepared breaker-tread structure 115 is attached to the central part ofthe trochoidal carcass 80_(a) and the carcass layer is tightly securedto the aforesaid structure. After completion of the adhesive securingthe transporting device J moves back to the waiting position and formingoperation under pressure continues to be conducted for a green case onthe drum D in accordance with the predetermined operational order.

The positional state on the drum D at this time is as illustrated inFIG. 7(c).

When operations on the drum D are over and thereby the required greentire is obtained, the transporting device J holds the green tire at theouter surface thereof, as illustrated in FIG. 9(i).

After completion of the foregoing holding operation the shoulder formersD₃ and D₄ and the bead lock seals 113 are contracted.

The positional state on the Drum D at this time is as illustrated inFIG. 7(d). The finished green tire is removed from the drum D with theaid of the transporting device J and thus a series of operations havebeen completed.

It will be readily understood from the above description that atrochoidal green tire is manufactured by way of the steps of expandingthe carcass band-bead core assembled structure prepared on the former Ato a cylindrical configuration in the area between both the bead cores,causing the shoulder formers to expand in the cylindrical space,effecting assembly to a cylindrical green case and then deforming thelatter to a trochoidal configuration.

Alternatively, the following steps may be employed as briefly describedbelow.

Namely, a required trochoidal green tire is manufactured by way of thesteps of expanding the carcass band-bead core assembled structureprepared on the former A to a cylindrical configuration in the areabetween both the bead cores on the former A, transporting the assembledstructure to the drum D with the above configuration maintained, causingthe shoulder formers to expand in the cylindrical space, effectingassembly to a cylindrical green case and deforming the latter to atrochoidal configuration.

When the above alternative method is employed, it is of course necessarythat the former A and the transporting device C are designed andconstructed in a different manner from the foregoing. For instance, aproposal made by the same applicant under Japanese patent applicationNo. 65725/81 may be available for the present invention.

As will be readily understood from the above description, the presentinvention makes it possible to effect assembling of a carcass layer in astrictly exact manner.

Particularly, it is possible that a carcass ply cord is located in exactalignment with the inner face of the bead cores, that is, a carcass plycord manufactured in the preceding step (calendar process) under acorrect control is attached to the inner face of the bead cores withoutany damage or injury caused thereon.

Further, when the intermediate portion between both the bead cores ofthe ply is mounted on a practically solid cylindrical body which has adiameter larger than that of the bead cores, it is possible to preventthe ply cord from being located in a wrong alignment with the drumshoulder portions and thereby effect assembling of a cylindrical carcasslayer on the practically solid cylindrical body in a strictly exactmanner.

Thus, the present invention makes it possible to effect assembling of agreen tire by attaching a trochoidal breaker and a tread without anynecessity for displacing the cylindrical carcass layer, resulting in animproved productivity for manufacturing radial tires.

Finally, it should be noted that tire manufacturing at an excellentlyhigh efficiency is ensured because of the fact that a NO. (N+1) carcassband is prepared on the drum A while a NO. (N) tire is assembled on thedrum D.

The present invention has been described above only with the preferredembodiment of the invention, but it should be of course understood thatit should be not limited only to this and it may be changed or modifiedin a suitable manner without any departure from the spirit and scope ofthe invention.

What is claimed is:
 1. A method of manufacturing a green radial tire having a carcass ply and a pair of bead cores, comprising: forming the carcass ply into a cylindrical shape having an external diameter almost equal to an internal diameter of the bead cores; subsequently transforming the cylindrical carcass ply to assume a circumferentially wave-shaped corrugated carcass ply over an entire length thereof in the axial direction while containing an outer diameter of the carcass ply; arranging a pair of bead cores in selected positions on the wave-shaped corrugated carcass ply which has been contracted in diameter; then normalizing the carcass ply into its cylindrical shape so as to form a structure having the pair of bead cores in contact with the external surface of the carcass ply; expanding the carcass ply in diameter in an area thereof between the pair of bead cores of the structure; then bending end portions of the carcass ply disposed axially outside of the bead cores so as to enclose the bead cores therein within portions of the carcass ply; then assembling a cylindrical carcass layer by incorporating side-wall members with the structure; and transforming said cylindrical carcass layer into a torroidal shape thereby forming a green tire.
 2. A method of manufacturing a green tire structure, comprising:forming a carcass ply into a cylindrical shape, said carcass ply having an axial length with an external diameter being at most slightly less than an internal diameter of a pair of bead cores; changing the shape of said carcass ply to reduce its maximum external diameter and form said carcass ply into a circumferentially corrugated shape which is corrugated along the full axial length of the carcass ply; positioning a pair of bead cores adjacent opposite axial ends of said carcass ply having the circumferentially corrugated shape, an end portion of said carcass ply remaining adjacent each bead core and a central portion of said carcass ply disposed between said pair of bead cores; returning said carcass ply to its cylindrical shape and to a diameter sufficient to engage the carcass ply with each of the bead cores; expanding the central portion of the carcass ply between the pair of bead cores to increase the central portion to a diameter greater than a diameter of said bead cores; bending each end portion of the carcass ply over each bead core respectively to enclose each bead core within portions of said carcass ply; and transforming the carcass ply with enclosed beads into a torroidal shape with the central portion of said carcass ply bulged radially outwardly to form the green tire. 